When dip coating small diameter cylindrical substrates, a major problem is the reliable insertion of the chucking device into the open end of the substrate. This is because the substrate must be held vertical but still must be able to be removed from its supporting device (which may be in the form of a pin). This means the supporting device must allow some clearance between the supporting device and the substrate, resulting in the substrate being slightly off-center from the exact vertical position. Over the length of a long substrate, the top end of the substrate could be significantly out of position. When this happens, it becomes difficult to reliably insert the chucking device into the substrate.
There is a need, which the present invention addresses, for a chucking device that can reliably center and hold off-center substrates.
Conventional chucking devices are disclosed in Mistrater et al., U.S. Pat. No. 5,328,181; Mistrater et al., U.S. Pat. No. 5,829,760; and Schmitt et al., U.S. Pat. No. 5,794,948.